Mobile vehicles, such as lift trucks, are normally mounted on pairs of front and rear wheels for locomotion purposes. The rear pair of wheels of a lift truck are normally steerable to guide the truck into various work positions. Although lift trucks of this type function satisfactorily, their turn radius and maneuverability, especially in narrow aisles, is limited due to the standard steer axle arrangement wherein steerable wheels are pivotally mounted on a frame of a truck by vertically disposed king pins.
Attempts have been made to provide vehicles of this type with multi-directional capabilities by modifying the ground engaging or tractive components thereof. For example, U.S. Pat. No. 2,999,554, issued on Sept. 12, 1961 to J. H. Wagner, discloses a vehicle having endless treads for selectively moving a vehicle in different directions by adjusting the orientation of the treads relative to ground level. However, endless treads of this type have a limited turning radius and maneuverability because they are positionable relative to the ground level or supporting surface only in a direction either parallel to or normal to the longitudinal axis of the vehicle. In addition, such vehicles are relatively slow in their travel and direction change.
The present invention is directed to overcoming one or more of the problems as set forth above.